McNICHOLS® Quality Grating - Bar Products

With Press-Locked Grating the cross bars and bearing bars are notched and pressed together through a high pressure manufacturing process. The result is a bi-direction flush surface that assures a firm, rigid connection and makes it aesthetically appealing for architectural applications. It is available from stock in twp bearing bars heights, in plain or corrosion-resistant galvanized steel, or aluminum. A variety of other bar heights, bar spacings and materials is available by special order. If your application requires a closer bar spacing, McNICHOLS® Close Mesh Grating may better serve your needs.

To place your order, please indicate your quantity in the stock list below.

Pressure-locked means bearing bars are locked in position by cross bar deformation instead of riveting or welding. Typically, the bearing and cross bars contain slotted openings that are aligned in an egg-crate fashion. Then, the bars are pressed under intense hydraulic pressure. The result is a flush top with excellent lateral stability and standing comfort.

Press Locked Series

McNichols’ press-locked products are divided into four series—each with specific bearing and cross bar spacing, bearing bar sizes, weights, load characteristics, fastener requirements, etc. Links to press-locked series information are provided below. Press-locked is also available as a Close Mesh series.

Note: The GAA, GBB, GCC & GDD Series are not suitable for barefoot pedestrian or wheel traffic. See Close Mesh for an additional press-locked series. Press-Locked will not have the discoloration typical of welded stainless steel bar grating and can be used instead of welded bar grating where appearance is a primary concern.

Note: For stainless steel, the standard mill finish will be gray and will have a discoloration of various colors (blue, black, brown, etc.) as a result of the heat generated in the welding process in manufacturing of the grating. Sandblasting is available to improve the appearance.

Center to Center bearing bar spacing is the of distance from the center of one bearing bar to the center of the next bearing bar. See the spacing table for more information on the GAA, GBB, GCC & GDD series center to center bearing bar spacing.

Press-Locked Grating bearing and cross bars contain slots that are aligned in a egg-crate fashion, Then, the bars are pressed together under tremendous hydraulic pressure that locks the bars in place. Press-locked grating™ strength is similar to welded bar grating, but the appearance is more suitable to architectural applications. Press-Locked grating should not be used for wheel or barefoot pedestrian traffic.

The bearing bars run parallel to the length or span of a standard grating panel and are responsible for the product’s load bearing capabilities. The cross bars, which run parallel to the width of the span, are primarily responsible for holding the bearing bars together. However, they also play a factor in deflection characteristics, especially for concentrated loads which are not distributed across the span of the grating.

Bar grating panels, pieces, or trench grating can be banded to provide strength and to provide a finished look. Banding is the welding of a rectangular metal bar to the ends of the bearing bars. Two banding types are available, based on the placement of the welds.

· Load Banding - The metal bar is welded at every bearing bar. Load banding is commonly used in trench grating applications where high loading requirements exist (i.e. motorized wheel traffic). Note: Aluminum products are not load banded.
· Trim Banding - The metal bar is welded only at every 4th to 6th bearing bar. Trim banding is commonly used for pedestrian traffic applications where loading is not a factor.

The bearing bar height, also known as bearing bar depth, is measured from the bottom of the bearing bar to the top. See the appropriate GAA, GBB, GCC or GDD Series load table for available bearing bar heights.

The bearing bar thickness, also known as bearing bar width, is the measurement of distance between the left surface of the bearing bar to the right surface of the same bearing bar. The standard rectangular bearing bar thickness for welded grating is 3/16 inch. A smaller bearing bar thickness is available in 1/8 inch .

The span of the grating is the length of the grating between grating supports. In order to perform in accordance with its design loading characteristics, grating must be installed so that the bearing bars are parallel to the span. This is necessary because bearing bars are the primary elements which support the load applied to the grating.

Clear span is the length of unsupported grating. Grating supports typically have a foot or ledge on which the grating rests. The part of the grating resting on the support is not part of the clear span. For example, if a 36-inch long piece of grating rests on two supports, each with a 3-inch ledge, the clear span would be 36 inches minus the part of the grating resting on the ledge (which is a total of 6 inches). In this example, the clear span would be 30 inches.

When selecting a specific bar grating, it is important to know how much the grating will deflect (i.e. bend) under load. Deflection is determined by consulting a load table.

Types of load
Grating applications are subject to two common load types: Uniform and Concentrated.

Uniform Load
Uniform load is applied equally to the full width and span of the grating . It is measured in pounds per square foot.

Concentrated Load
Concentrated load is applied to the full width of the grating at mid-span and is not equally distributed across full length of the span. Concentrated load is measured in pounds per foot.

Grating in some applications may be subjected to a concentrated load over only a portion of its width. This is called a partial load. The deflection in a partial load is determined by the stiffness of both the bearing bars and the cross bars, and varies with the type of grating used. To determine carrying capacity of gratings subject to partial loads, click on live help, email us at internet.sales@mcnichols.com or call McNICHOLS (1-800-237-3820).

If you don’t know the bearing bar height and thickness you require, the appropriate grating size can be determined from the load the grating is expected to carry. The following information is required.

What type of traffic will the grating support?
If only people are supported, specify pedestrian. If wheel traffic is to be supported, choose between "on-" or "off-road" vehicles. On-road vehicles include trucks, cars or any other vehicles that could be registered and licensed. If the vehicle would not typically be registered, a construction vehicle or forklift, for example, then specify "off-road."

For Wheel Traffic Only
If the traffic includes off-road vehicles, then it is necessary to know:

· Weight or capacity of the vehicle in pounds
· Wheel diameter in inches
· Width of wheel in inches
· The tire type, either solid or pneumatic (air filled)

The standard panel length is 12 feet. Other panel lengths are available by special order. Panels may also be cut-to-size.

The bearing bars run the length of the panel and this is also the direction of the grating span that provides optimum loading capacity. Please consult the appropriate load table for application requirements.

Bar Grating can be cut three ways to produce three different types of stubs: random, uniform, or equal stub. The cutting costs vary according to the material, number of cuts, and type of cut.

Random cut
This is the most cost effective cut and is standard. When two equally-sized, randomly-cut pieces are placed side-by-side, the cross bars may not line up. The measurements for equal pieces will be the same; however, the distance from the bearing bar ends (stubs) to the cross bars will vary from piece to piece and end to end.

Uniform cut
When two equally-sized, uniformly-cut pieces are placed side-by-side, the cross bars will line up, but may not be centered. The measurements for equal pieces are the same; however, the distance from the bearing bar ends (stubs) to the cross bars will not be the same on both ends but will be uniform from piece to piece.

Equal Stubs
When two equally-sized pieces with equal cut stubs are placed side-by-side, the cross bars will line up and will be centered. The measurements for equal pieces are the same and the distance from the bearing bar ends (stubs) to the cross bars will also be the same on both ends.

Open space is the clear spacing between the bearing bars. It is also the difference between the bearing bar thickness and bearing bar center to center spacing. For example, open space for GAA bar grating with a 3/16 inch bearing bar thickness is 1 inch (1–3/16 inch bearing bar centers - 3/16 inch bearing bar thickness = 1 inch open space). The table to the right lists the press-locked bar grating open space.

Open area is the total area of the space between the cross and bearing bars divided by the total area of the bar grating panel and is expressed as a percent. The larger the open area, the higher the percentage of light, air, or fluid that can pass through the grating.